Emma Stone candidly opened up about her mental health struggles during a talk on Monday, recounting how she once suffered from such crippling anxiety attacks her family once thought she would never be able to move away.

The actress, 29, spoke with the president of the Child Mind Institute, Dr. Harold Koplewic, in New York City at the AMC Lincoln Square.

She explained that her first panic attack occurred before she started second grade, while she was at a friend's house.

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Speaking out: Emma Stone, 29, candidly opened up about her mental health struggles during a talk on Monday in New York City at the AMC Lincoln Square

'I was over at a friend's house and all of a sudden I was absolutely convinced the house was on fire and it was burning down.

'I was just sitting in her bedroom, and obviously the house wasn’t on fire but there was nothing in me that didn't think we weren't going to die.

'And so I called my mom and it was panic but I of course didn't know that and she came and picked me up. It just kept going for the next two years.'

Throughout second grade, Emma was able to go to school but would go to the nurse's office every day at lunch and tell the nurse she was sick and needed to go home.

She couldn't go to her friends' houses and experienced deep anxiety when she was separated from her mother. Her anxiety escalated to the point that if her mom Krista had to come to school, Emma couldn't bear to see her because it would send her into a 'whole tailspin'.

At one point, Emma also needed her mother to tell her the day's schedule ahead of time and repeat it several times to calm her fears — until Emma's therapist told Krista she should only go through the schedule once with her daughter.

'I was so kind of paranoid about everything and it got to the point where if she needed to come help at school I couldn't see her but I needed to know exactly what the day was going to be,' Emma said.

'And she would repeat it over and over to me until thankfully I had a therapist who said: "You're allowed tell her once and then you can't say it anymore, because she needs to not constantly rely on you telling her the day."'

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Conversation: The actress told the president of the Child Mind Institute, Dr. Harold Koplewic, that she had her first panic attack before entering the second grade

When it became clear that the panic attacks were becoming a pattern, Emma started going to therapy, for which she remains 'so grateful'.

Doctors told Krista that Emma was suffering from general anxiety disorder or a version of panic disorder but Emma wasn't privy to the diagnosis, which she said she's also grateful for.

The actress described how isolating the condition was and explained her friends were too young to relate to it, meaning she couldn't truly discuss it with them.

'I spoke more to my family about it than my friends because friends at that age, eight-year-olds aren't going to understand, "Oh no I can't leave the house because if I do, my mom will die,"' she said.

'It wasn't true but that's what I felt. Nobody can relate when you're a kid, which I think is understandable.'

While attending therapy as a child, Emma wrote a book named I Am Bigger Than My Anxiety, for which she drew pictures, and represented her anxiety as a small green monster.

She explained that this helped her to see the condition as only a part of her identity, rather than her whole self.

Little Emma: The 29-year-old actress (pictured as a girl) said she's 'so grateful' to have attended therapy as a child

While Emma's family once thought she would never be able to move away from them, the Arizona native famously relocated to Los Angeles when she was just 15 years old to pursue a career in acting, after making her case through a PowerPoint presentation titled 'Project Hollywood'.

She eventually convinced her parents to let her go to LA with her mother while her father stayed in Scottsdale.

'It's nuts that they agreed to it,' Emma previously told The Hollywood Reporter. 'I don't condone it. Everybody should go through high school and graduate.'

The move came as a surprise for the family given Emma's history of separation anxiety.

'We truly thought I wasn't going to be able to move out of the house and move away ever,' she said. 'How would I go to college, how would I do any of this when I couldn't go to a friend's house for five minutes?'

Asked whether she still feels her anxiety holds her back in any way as an adult, Emma said she would like to be able to speak out more freely about a variety of topics.

'A lot of sharing, speaking about certain issues or things or making mistakes is a very big trigger fear for me,' she said. 'I would like to be more outspoken about a lot of things and I know I will learn to be if that's appropriate for me but that's been a big challenge for me.'

This is not the first time Emma has opened up about her mental health struggles. She did so in May last year in a video for the Child Mind Institute, in which she explained she once thought anxiety would affect her forever.

'I truly, as a kid, did not think I would be able to ever move away from home or to be away from people that I had separation anxiety with,' she said in the candid clip. 'I've been able to manage that with great therapists and great cognitive behavioral tools — meditation and lots of things.'

Looking ahead: Asked whether she still feels her anxiety holds her back in any way as an adult, Emma said she would like to be able to speak out more freely about a variety of topics

The actress stressed that anxiety does not last forever, although it might seem that way in dire times.

'Life goes in stages, and it has always been something that I've lived with and that flares up in big ways at different times in my life,' she said. 'But sometimes when it's happening, when I'm in a phase of real turmoil or the anxiety is very strong, it feels like the anxiety is never going to end, and it does.'

Emma was one of a series of celebrities taking part in the Speak Up For Kids campaign, for which several A-listers recorded videos in which they give advice to their younger selves for handling mental health issues.

In another clip for the campaign, Emma urged other children struggling with anxiety to know they are not alone.

'It's so normal. Everyone experiences a version of anxiety or worry in their lives and maybe we go through it in a different or more intense way for longer periods of time, but there's nothing wrong with you,' she said.

'To be a sensitive person that cares a lot, that takes things in in a deep way, is actually part of what makes you amazing and is one of the greatest gifts of life.'

She then explained that she wouldn't trade her ability to 'feel a lot' and 'feel deeply' for the world, even when faced with hard times.

'There are so many tools you can use to help yourself in those times and it does get better and easier as life goes on, and you start to get to know yourself more and what will trigger certain instances of anxiety and where you feel comfortable and safe,' she said.

'Don't ever feel like you're a weirdo for it, because we're all weirdos.'